A spike in serious black-lung cases in eastern Kentucky indicates that a disease lawmakers hoped to eradicate decades ago continues to afflict miners.

Researchers found that 60 current or former coal miners who were patients of a single radiologist showed evidence of the most severe form of black lung, according to a report released Thursday by the National Institute for Occupational Safety and Health.

The miners – nearly all of them from Pike, Floyd, Letcher and Knott counties – were diagnosed with progressive massive fibrosis between January 2015 and last August, the report said.

There were only 31 cases of progressive massive fibrosis identified nationwide from 1990 to 1999, according to the report. Prevalence of black lung had declined steadily for several decades, dropping to 2 percent in screenings conducted from 1995 to 1999, NIOSH said in a May 2011 report. Then, mysteriously, black lung rebounded. Screenings in 2005 and 2006 found the disease in 3.3 percent of surveyed miners.

Black lung is caused from breathing dust churned up during coal mining. The incurable disease chokes off a person’s ability to breathe and often leads to premature death.

It has been the cause of about 78,000 deaths since 1968, Joe Main, head of the federal Mine Safety and Health Administration, said in a conference call this week.

Congress approved a law in 1969 that set limits on miners’ exposure to breathable dust.

The goal was to wipe out progressive massive fibrosis, according to the NIOSH report released Thursday.

The incidence of the disease fell sharply after the 1969 mine act.

However, there has been a resurgence of black lung in Central Appalachia in recent years, and the “ongoing outbreak” of cases seen at the Eastern Kentucky clinic in 2015 and 2016 “highlights an urgent need for effective dust control in coal mines,” the new NIOSH report said.